In recent years, the use of light-emitting diodes (LEDs) for various common lighting purposes has increased, and this trend has accelerated as advances have been made in LEDs and in LED-array bearing devices, referred to as “LED modules.” Indeed, lighting needs which have primarily been served by fixtures using high-intensity discharge (HID) lamps, halogen lamps, compact florescent light and other light sources are now increasingly beginning to be served by LEDs. Creative work continues in the field of LED development, and also in the field of effectively utilizing as much of the light emitted from LEDs as possible.
As is known, LED “packages,” which typically consist of a single LED (or small LED cluster) on a base with or without a “primary lens,” each have an individual lens thereover to direct light from the LED package as intended. (Such lens is sometimes referred to as a “secondary” lens when the package with which it is used includes a primary lens.) Development efforts have been made in the field of such lenses, with the intention being to redirect some of the package-emitted light in a manner forming illumination patterns desired for particular applications. However, such lenses have tended to fall short of the most desirable performance in that some LED-emitted light is lost.
Typically, some of the light from LEDs is emitted at angles that cause LED-lighting fixtures to provide less than desirable and less than fully efficient illumination patterns. Some prior lenses have been configured to prevent undesirable light from exiting the lens and others to block such light immediately upon its exiting the lens. Even though these configurations were deemed necessary to achieve desired illumination patterns and to prevent so-called lighting “trespass,” they tended to result in lost light and decreased efficiency of LED illuminators. It would be highly desirable to improve efficiency of the use of light emitted by LEDs in lighting fixtures.
A typical LED emits light over a wide range of angles such that light from the LED reaches a particular area of the output surface of the lens at somewhat different angles. This has made it very difficult to control refraction of such light. As a result, only a portion of light being refracted is refracted in a desired direction, while the remainder exits the lens with very little control. It would be desirable to provide improved control of the direction of light exiting such lenses.
Trespass lighting can be evaluated by more than just the amount of light emitted in an undesired direction; also to be considered is how far from the desired direction such light is directed. It would be highly beneficial to provide a lighting apparatus which produces a desired illumination pattern with a maximum amount of light emitted toward the space intended to be illuminated, in typical commercial applications.